TAGRA 2024

Abstract: The properties of synthesized carbon quantum dots (CQDs) depend on the precursor type and synthesis method. Therefore, selecting an appropriate precursor is the first step in the controlled production of CQDs. The synthesis method should be simple, environmentally friendly, and utilize materials that can replace conventional toxic substances. For this purpose, a green approach is employed to produce carbon dots using naturally occurring precursors. In this study, the precursors include Jasminum polyanthum flower extract, rich in secondary metabolites, and chicken nails as a source of keratin. The ethanolic extract of Jasminum polyanthum flower was prepared via maceration, and the chicken nail solution was obtained through acidic digestion. CQDs, due to their properties such as excellent water solubility, photostability, and chemical stability, have been employed as sensors for detecting Pb²⁺ metal ions in solutions. In this method, fluorescence quenching occurs as a result of complex formation between lead ions and the carbon quantum dots. Photoluminescence (PL) analysis of the synthesized CQDs showed an excitation wavelength of 330 nm and an emission wavelength of 430 nm. Key parameters affecting synthesis, including solvent selection, synthesis temperature, synthesis time, pH, and carbon source concentration. Jasminum polyanthum flower extract was studied and optimized. Between water and ethanol, ethanol was selected as a solvent, 160 ◦C as synthesis temperature, pH=12, nail solution 500 ppm, and Jasminum polyanthum flower extract 300 ppm were selected.
The surface of CQDs is modified with nitrogen, sulfur and fluorine to enhance the detection limit. GC-MS analysis was performed to separate and identify the secondary metabolites present in the ethanolic extract of Jasminum polyanthum. Structural and functional characterization was performed using FTIR, PL, and UV-Vis spectroscopy, to analyze the size distribution DLS technique and CHNSO for elemental analysis.